Is Blood-Pressure Control Safer With Small Doses of More Meds?

Research suggests smaller doses of a few medications may be better than a large dose of a single drug. But that approach may not apply in all cases.

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When blood pressure control requires medications, you and your doctor have many options. There are dozens of types of antihypertensive drugs, and within each class of drug there are dozens more brand and generic options.

The goal, of course, is to find the right medication (or combination of medications) that does the job without harmful side effects. For many people, two or more drugs are needed to get their blood pressure into a healthy range. For others, a strong dose of a single medication is enough to lower their blood pressure. But sometimes that leads to unwanted side effects.

A recent study published in the American Heart Association journal Hypertension found that taking quarter doses of two antihypertensive medications was as safe and effective as one standard dose of a medication. Researchers also found that taking quarter doses of four medications was about twice as effective at lowering blood pressure as one standard dose, and that there were far fewer side effects associated with taking four quarter doses.

“The principle of the quarter dose does make sense,” says Steven Nissen, MD, chairman of the Department of Cardiovascular Medicine at Cleveland Clinic. He notes that such findings haven’t been supported by a large clinical trial, however.

Rethinking Strong Doses

Cardiologists have learned through the years that they can achieve excellent results with lower doses of established medications. For example, Dr. Nissen says that there was a time when the diuretic chlorthalidone was typically prescribed at 50 milligram (mg) doses. But large doses of diuretics can dramatically change fluid levels in the body and raise the risk of causing low, unhealthy blood potassium levels.

“We’re now giving patients 12.5 mg of chlorthalidone, which is, of course, a quarter dose,” Dr. Nissen says. “We have learned these lessons.”

Doctors have also learned that you don’t necessarily achieve much benefit by prescribing larger doses. In the case of the calcium channel blocker amlodipine, 80 percent of blood pressure control is achieved at 2.5 mg, Dr. Nissen says. The drug is usually prescribed in doses ranging from 2.5 to 10 mg. With little benefit, but an increased risk of side effects, higher doses don’t always make sense, Dr. Nissen says.

“If you know the drug well, you know that if you push the dose, you’re going to get unwanted side effects in some cases,” he adds. “The best doctors, when treating hypertension, know the benefits and risks of the drugs they’re prescribing and they communicate that information to their patients.”

Managing Multiple Drugs

When more than one type of antihypertensive drug is necessary to control blood pressure, doctors face some common questions: Will my patient remember to take all the medications and at the right times during the day? Dr. Nissen says medication adherence is a big concern, and is often the reason why some patients can’t keep their blood pressure well controlled.

Recently, pill taking has been somewhat simplified with combination drugs. Pills containing an ACE inhibitor and a calcium channel blocker or an ACE inhibitor and a diuretic are widely prescribed. They reduce the numbers of pills you have to take and they help reduce drug costs. Dr. Nissen says these options can help, but a “one size fits all” approach isn’t ideal. “Customization of treatment is always the way to go,” he says.

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